In an image forming apparatus configured to form an image electrophotographically, a transfer member is provided on an inner side of an endless belt for conveying a sheet such that the transfer member faces a photosensitive member with the endless belt being interposed therebetween. By applying transfer bias to the transfer member, developer (toner) carried on the photosensitive member is transferred onto a recording sheet conveyed by the endless belt.
In this image forming apparatus, in order to remove developer, paper dust, and so forth attached to the endless belt during an image forming (printing) operation, a cleaning member is provided to face an outer circumferential surface of the endless belt. In general, after printing completes, a cleaning bias is applied to the cleaning member, whereby the developer and so forth on the endless belt is transferred onto the cleaning member so as to be collected. Further, there is also known an image forming apparatus which applies a constant cleaning bias (voltage) to a cleaning member even during printing in order to remove the developer and so forth from the endless belt,